A human has two ears. The path of audio from an audio source to the left ear is typically different to the path of audio from the audio source to the right ear. An important audio cue for a human is the time difference (phase difference) between the path to the left ear and the path to the right ear. However, phase difference alone as a cue creates positional ambiguity because a locus of a sound source for a particular phase difference is typically a circle centered on a line passing through both ears rather than a point.
The human head and body diffracts sound waves. The effect is more anisotropic in the up/down directions than the left/right directions. An amplitude difference (level difference) between the path to the left ear and the path to the right ear may give a cue that enables a human to position the audio source up or down but may be insufficient to position a source front/back.
There exists a problem of how to render spatial audio (surround sound) using a multi-loudspeaker configuration. It may be that the microphone configuration introduces an ambiguity in the position of a sound source which may result, for example, in the sound source being rendered behind a listener when it should be rendered in front of the listener or may result in the sound source being rendered in front of a listener when it should be rendered behind the listener.